1. Field of the Invention
The present invention relates to a solar cell module, more specifically, to a solar cell module panel which is installed on a roof of a building or the like at low cost, whose installation and maintenance can be easily done, and which has long-term reliability, especially with respect to protection of the solar cell modules.
2. Related Background Art
Recently, photoelectric conversion devices such as solar cells have been developed to serve as what is called a "clean energy source." Solar cell modules serving as a power source have a plurality of solar cells held between glass plates or the like, or have a thin film solar cell element formed on a substrate such as a stainless steel substrate and encapsulated with a high polymer resin. Such solar cell modules are installed on a foundation such as a roof, wherein an installation base is fixed to rising portions of the roof and the solar cell module is fixed to said installation base. If there are not such rising portions, portions are formed on the roof in order to mount the installation base on which the solar cell modules are mounted.
FIG. 8 shows an example of the above solar cell module mounted on a roof by means of a solar cell installation base. The solar cell installation base 34 is fixed to the tops of protruberanes 36, which are seam portions of roof battens, through fastening members 35. At said seam portions, edges of adjacent metal roof rafters are folded together so as to be fastened to each other. Each solar cell module 37 has an aluminum frame. These solar cell modules 37 are fixed to the solar cell installation base 34 with respective fasteners (not shown).
The solar cell modules 37 are electrically connected through connectors 38 provided beneath them.
In the above-mentioned apparatus in which the solar cell installation base is used, since the connectors and cables are provided beneath the solar cell modules, they are not exposed to direct sunlight. Accordingly, the connectors and the cables do not have to be made of relatively expensive weather proof material, which is advantageous for reducing the cost of the connector units. In addition, as the connectors can be hidden beneath the solar cell modules, the external appearance of the installed solar cell modules is good. In this method of installation, however, the material cost and the manufacturing cost of the solar cell installation base cancels out the above-mentioned advantage of the low cost of the connector units, and even make the total cost of this type of installation higher. And the base fixed on the roof of the building is not preferable with respect to its appearance. Further, the solar cell module held between glass plates weighs as much as 13-15 kilograms per square meter, and thus, is hard to handle when set up on the roof, etc., and the heavy installation base must first be fixed on the roof and the solar cell modules then fixed thereon with fasteners such as bolts. Therefore, it takes a long time and is dangerous to set up and mount the solar cell, and the base is expensive.
In order to solve the above-mentioned drawbacks, a method by which the solar cell modules are directly fixed to the roof rafters, as shown in FIG. 9, has been devised.
FIG. 9 shows an example in which the solar cell modules are directly fixed on the roof rafters with double-sided pressure sensitive adhesive tape. This method will be briefly described below with reference to FIG. 9.
Reference numeral 39 indicates a roof rafter, 40 indicates a solar cell module, and 41 is double-sided adhesive coated tape for adhering the solar cell module to the roof rafter. Reference numerals 42, 43, and 44 indicate a connector, a cable, and a junction box for leading out a terminal, respectively. The connector, the cable, and the junction box connect solar cell modules with each other.
In this method, as the solar cell modules are directly fixed to the roof rafters which can give the solar cell modules enough structural strength, the solar cell modules do not have frame and are as flexible as the solar cell elements sealed inside with resin. The solar cell modules are adhered to the roof rafters with double-sided adhesive coated tape, and are electrically connected with each other through said connectors 42 provided on the upper side of the modules.
The method in which the solar cell modules are directly fastened to the roof rafters by means of double-sided adhesive coated tape or the like does not require the solar cell installation base, whose cost can thus be eliminated. In this method, however, the solar cell modules do not have frames but are made of flexible solar cell elements sealed with resin; that is, the edge portions of the modules are not fixed nor protected by fasteners. Thus, if a worker hits a module with a tool or scratches it with a spiked shoe during installation of the solar cell, the module may be damaged; for example, the surface coating material can come off at the edge portion of the module. Accordingly, in order to improve long-term reliability, members for fixing and protecting the edge portions of the modules should be provided.
Further, as shown in FIG. 9, since the clearances between the solar cell modules and the roof rafters, which are provided by the double-sided adhesive coated tape are as narrow as about 1 mm, the connectors cannot be arranged or hidden behind the solar cell modules. Thus, relatively expensive weather proofed connectors must be used. And, when the solar cell module is set up in a windy area, the connectors or the cables have to be fixed with adhesive tapes or the like so that the connector units do not sway in the wind.
In addition, some users are not pleased with the appearance when the connector units are exposed.
As described above, there have been no methods of installing the solar cell modules in which the cost is low and, at the same time, long-term reliability is improved with respect to fixation and protection of the edge portions and electrically connecting units of the solar cell modules, especially with respect to protection of the solar cell modules. Accordingly, a method of installing the solar cell on a roof or the like of a building is desired in which the cost is low and, at the same time, long-termed reliability is improved especially with respect to protection of the solar cell modules.